A NOVEL FRAMEWORK OF ONLINE NETWORK CODING FOR MULTICAST SWITCHES WITH CONSTRAINED BUFFERS

Network coding is able to address output conflicts when fanout splitting is allowed for multicast switching.Hence,it successfully achieves a larger rate region than non-coding approaches in crossbar sw...     

On an efficient NoC multicasting scheme in support of multiple applications running on irregular sub-networks

When a number of applications simultaneously running on a many-core chip multiprocessor (CMP) chip connected through network-on-chip (NoC), significant amount of on-chip traffic is one-to-many (multicast) in nature. As a matter of fact, when multiple applications are mapped onto an NoC architecture with applicable traffic isolation constraints, the corresponding sub-networks of these applications are mapped onto actually tend to be irregular. In the literature, multicasting for irregular topologies is supported through either multiple unicasting or broadcasting, which, unfortunately, results in overly high power consumption and/or long network latency. To address this problem, a simple, yet efficient hardware-based multicasting scheme is proposed in this paper. First, an irregular oriented multicast strategy is proposed. Literally, following this strategy, an irregular oriented multicast routing algorithm can be designed based on any regular mesh based multicast routing algorithm. One such algorithm, namely, Alternative Recursive Partitioning Multicasting (AL + RPM), is proposed based on RPM, which was designed for regular mesh topology originally. The basic idea of AL + RPM is to find the output directions following the basic RPM algorithm and then decide to replicate the packets to the original output directions or the alternative (AL) output directions based on the shape of the sub-network. The experiment results show that the proposed multicast AL + RPM algorithm can consume, on average, 14% and 20% less power than bLBDR (a broadcasting-based routing algorithm) and the multiple unicast scheme, respectively. In addition, AL + RPM has much lower network latency than the above two approaches. To incorporate AL + RPM into a baseline router to support multicasting, the area overhead is fairly modest, less than 5.5%.     

Service based communication for MPSoC platform-SegBus

MPSoC platforms offer solutions to deal with communication limitations for multiple cores on single chip, but many new issues arise within the context. The SegBus platform is one of the solutions for application deployment on multi-core applications. There are many applications where identical data is transferred from the same source towards different destinations. Multicast services may come as a performance improving factor for the interconnection platform, together with interrupt service.In this paper, the task is to analyze, how different services can be designed for the SegBus platform and observe the improvement in system performance. The designer can select the services according to the requirements. The running example is represented by the H.264 encoder. The SegBus platform architecture, the communication mechanism, the allocation of processing elements on the platform, the communication services and their implementation are the main topics elaborated here.     

Asymptotic throughput analysis of multicast transmission schemes

This paper demonstrates the use of extreme value theory in the asymptotic throughput analysis of wireless multicast and unicast for large number of users. Exact analysis of these schemes involves finding the probability distributions of maxima or minima of signal to noise ratios (SNRs). Jointly considering random user distribution and Rayleigh fading, exact distributions of these extreme values become complex and lack insights. On the other hand, asymptotic expressions obtained by using extreme value theory are quite accurate even for moderate number of users and they give insights about the performances without using simulations. The results of this analysis can be used in designing cellular unicast and multicast systems.     

Multicast with a new switching structure in optical networks

The emergence of new services demands for a multicast function in optical networks. At the same time, wavelength converters are introduced to increase the efficiency of wavelength usage. It is because of the high cost and complex architecture of optical multicast and wavelength conversion technology, that a new switch structure is introduced, in which optical splitters and wavelength converters are shared per-node. In order to accommodate this architecture, a multicast routing and wavelength assignment algorithm in a splitter–converter-sharing optical network and a changing link weight policy to balance network traffic are proposed. By extending RSVP-TE (Resource ReSerVation Protocol-Traffic Engineering) and OSPF-TE (Open Shortest Path First-Traffic Engineering), an optical multicast mechanism is provided, and message type, signaling flow, and finite state machine model are given. Simulations of NSFNET show that, when the number of splitters and converters are 50% and 12.5% of the full equipment respectively, the performance is close to the ideal case. Using a changing link weight policy can improve performance greatly, when there are enough splitters and converters.     

Minimum-energy broadcast and multicast in wireless networks: An integer programming approach and improved heuristic algorithms

Both integer programming models and heuristic algorithms have been proposed for finding minimum-energy broadcast and multicast trees in wireless ad hoc networks. Among heuristic algorithms, the broadcast/multicast incremental power (BIP/MIP) algorithm is most known. The theoretical performance of BIP/MIP has been quantified in several studies. To assess the empirical performance of BIP/MIP and other heuristic algorithms, it is necessary to compute an optimal tree or a very good lower bound of the optimum. In this paper, we present an integer programming approach as well as improved heuristic algorithms. Our integer programming approach comprises a novel integer model and a relaxation scheme. Unlike previously proposed models, the continuous relaxation of our model leads to a very sharp lower bound of the optimum. Our relaxation scheme allows for performance evaluation of heuristics without having to compute optimal trees. Our contributions to heuristic algorithms consist of the power-improving algorithm successive power adjustment (SPA), and improved time complexity of some previously suggested algorithms. We report extensive numerical experiments. Algorithm SPA finds better solutions in comparison to a host of other algorithms. Moreover, the integer programming approach shows that trees found by algorithm SPA are optimal or near-optimal.     

基于蚁群算法的树环结构应用层组播树构建算法

作为对IP组播技术的改进,应用层组播(ALM)技术具有不受网络架构限制、资源丰富、数据传输速率高等优势。综合考虑节点性能和端到端延迟,提出一种快速且高效的建立应用层组播树的方法：基于蚁群算法的树环结构ALM模型(ACOTRM)。目前对ALM结构的研究大部分都是仅仅粗略地给出拓扑结构,而对整个构建过程却缺乏完整且清晰的描述。鉴于此,完整地给出了一种树环结构ALM树的具体构建过程,主要包括网络节点分簇、簇内成环连接、数据转发数的建立等关键步骤。另外,为每个节点设定特有的优先级,使得整个ALM树达到最优化状态。仿真结果表明,该模型得到了较低的平均时延以及较高的平均数据传输率,在增加系统稳定性的同时也提高了其转发效率。     

基于泛洪约束的MANET按需组播路由协议

降低路由控制开销是MANET网络组播路由协议节省节点能量,提高带宽利用率的关键因素之一。本文研究了组播路径近邻节点对路由维护的作用以及链路的连通性,分别提出了一个新的泛k-洪约束算法和一个混合泛洪模式。基于泛k-洪约束算法和混合泛洪模式,提出一个新的按需组播路由协议ODMRP-CF,ODMRP-CF协议通过选择k-路由近邻节点转发泛洪分组来提高泛洪效率。ODMRP-CF协议不仅保持了ODMRP协议所具有的简单,对节点移动鲁棒性好的优点,而且有效地降低了ODMRP-CF协议的控制开销。     

一种支持单播与组播混合业务的高速Crossbar调度算法

当前在高速crossbar中支持单、组播混合业务调度的实用算法一般采用请求-许可-接受的处理流程(例如ESLIP算法)。研究发现,该类算法中存在单、组播许可相互阻塞现象,造成调度效率降低。从实用性出发,该文提出了一种新的支持单、组播混合业务的调度算法ERGRR(Extended Request-Grant-based Round- Robin),通过简化调度处理流程,克服了许可阻塞现象,提高了系统吞吐量、时延等性能。仿真结果表明,在单、组播混合业务流下,ERGRR算法吞吐量、时延等性能优于ESLIP算法。另外,ERGRR算法具有更好的公平性以及更加易于硬件实现。     

An efficient algorithm for group multicast routing with bandwidth reservation

Multicasting refers to the transmission of data from a source node to multiple destination nodes in a network. Group multicasting is a generalisation of multicasting whereby every member of a group is allowed to multicast messages to other members that belong to the same group. The routing problem in this case involves the construction of a set of low cost multicast trees with bandwidth requirements, one for each member of the group, for multicasting messages to other members of the group. In this paper, we propose a new heuristic algorithm to generate a set of low cost multicast trees with bandwidth requirements. Simulation results show that our proposed algorithm performed better in terms of cost and in terms of utilisation of bandwidth as compared to an existing algorithm that was proposed by Jia and Wang [3].